The physics of E × B-drifting jets

E × B-drifting jets have been generally ignored for the past 25 years even though they may well describe all the astrophysical jet sources, both on galactic and stellar scales. Here we present closed-form solutions for their joint field-and-particle distribution, argue that the observed jets are near equipartition, with extremely relativistic, monoenergetic e^±-pairs of bulk Lorentz factor γ ≲ 10⁴, and are first-order stable. We describe plausible mechanisms for the jets’ (i) formation, (ii) propagation, and (iii) termination. Wherever a beam meets with resistance, its frozen-in Poynting flux transforms the delta-shaped energy distribution of the pairs into an almost white power law,E ² N _E ∼E ^−∫ with ∫ ≳ 0, via single-step falls through the huge convected potential.     

Determining Field Correlations Produced by Stars from the Study of Spectral Changes in Double Slit Experiment

Experiments are performed to determine the coherence properties of wave fields, produced by the broadband stellar sources on the earth surface, from the study of spectral changes produced on interference in the Young's double slit experiment. The spectral degree of coherence obtained experimentally in this study for four bright stars in the wavelength range from 325 nm to 660 nm is in close agreement with the value that is expected theoretically from the known angular diameter of the stars. It is shown that the spectral degree of coherence obtained experimentally by this spectral interferometric technique could be used to determine the angular diameter of stars. This revised version was published online in July 2006 with corrections to the Cover Date. This revised version was published online in July 2006 with corrections to the Cover Date.     

A process-based approach to attribution of historical streamflow decline in a data-scarce and human-dominated watershed

Human activities have resulted in rapid hydrological change around the world, in many cases producing shifts in the dominant hydrological processes, confounding predictions, and complicating effective management and planning. Identifying and characterizing such changes in hydrological processes is therefore a globally relevant problem, one that is particularly challenging in sparsely monitored environments. We develop a novel, process-based approach for attribution of hydrological change in such scenarios and apply the approach to the TG Halli watershed outside Bangalore, India, where streamflow has declined considerably over the last 50 years. The approach consists of (a) employing a range of field instrumentation and experiments to identify contemporary streamflow generation mechanisms, (b) using these observations to constrain our understanding and generate hypotheses pertaining to historical changes, and (c) evaluating these hypotheses with a range of evidence including proxies for historical hydrological processes. The body of evidence in the TG Halli watershed indicates the historical presence and subsequent loss of a shallow groundwater table that previously discharged to the stream, meaning that groundwater depletion is the most likely driver of streamflow decline. These findings present a viable path towards improved predictions of future water resources and sustainable water management within the watershed. Our process-based approach to attribution has the potential to improve understanding of human-driven hydrological change in regions with poor monitoring of hydrological systems.     

Interpretation of Gravity Data using 3D Euler Deconvolution,Tilt Angle,Horizontal Tilt Angle and Source Edge Approximation of the North-West Himalaya

The collision of the Indian plate and the Eurasian plate created shortening and imbrications with thrusting and faulting which influences northward tectonic movement. This plate movement has divided the Himalaya into four parts, viz. Outer Himalaya, Lesser Himalaya, Greater Himalaya, and Tethys Himalaya. The crystalline basement rock plays an imperative role for structural and tectonic association. The study has been carried out near Rishikesh-Badrinath neighborhood in the northwestern part of the Himalayan girdle with multifarious tectonic set up with thrusted and faulted geological setting. In this study area, 3D Euler deconvolution, horizontal gradient analysis, tilt angle (TILT) and horizontal tilt angle (TDX) analysis have been carried out using gravity data to delineate the subsurface geology and heterogeneity in the northwestern part of Himalaya. The Euler depth solutions suggest the source depth of about 12 km and various derivative analyses suggest the trend of the delineation thrust-fault boundaries along with the dip and strike direction in the study area.     

Reductive Dechlorination of PCBs Using Photocatalyzed UV Light

Feasibility of photocatalytic dechlorination of PCB‐138 and Aroclor‐1254 using platinum loaded TiO₂ (P25) in an alkaline 2‐propanol medium has been investigated. Experiments were conducted in batch mode using a Rayonet photo‐reactor under aerated and deaerated conditions with black lamps emitting around 350 nm as light source. Two forms of platinum deposition were investigated: Photochemically loaded P25 as well as addition of potassium hexachloroplatinate into the reaction medium. Partial dechlorination of PCBs was observed after 7 h of irradiation with pure TiO₂ as catalyst when the reaction vessel was kept open to air. Complete dechlorination was observed after 5 h of irradiation in a deaerated environment. Enhanced photocatalytic efficiency was observed when platinum deposited P25 was used as catalyst, with the best result being obtained when aqueous potassium hexachloroplatinate was added into the reaction medium. Lower potassium hexachloroplatinate concentration (0.1 mM) yielded better performance.     

Centrifuge modelling of the seismic performance of soft buried barriers

The paper presents the results of an experimental work carried out in a geotechnical centrifuge at the Schofield Centre of Cambridge University. Two reduced scale models of soft barriers in a sand layer underwent a series of ground shaking. In the first model a thin horizontal layer made of latex balloons filled with a cross-linked gel was created at about mid-height of the sand layer. In the second, the same balloons were deployed to form a V-shaped barrier aimed at isolating a relatively shallow volume of sand. The aim of the study was to get experimental evidence of the capability of such soft barriers to isolate a volume of soil thus reducing amplification of ground motion during severe seismic events. The experimental results were compared with FE numerical analyses of the same models, carried out also in free field to have a benchmark condition. By validating the FE modelling via the comparison with the experimental results, a robust model has been built, aimed at being used for carrying out a wider parametric numerical testing. The experimental results confirm the effectiveness of such soft barriers to reduce amplification in the isolated volumes during seismic events.     

Einstein’s gravity under pressure

The mysterious ‘dark energy’ needed to explain the current observations, poses a serious confrontation between fundamental physics and cosmology. The present crisis may be an outcome of the (so far untested) prediction of the general theory of relativity that the pressure of the matter source also gravitates. In this view, a theoretical analysis reveals some surprising inconsistencies and paradoxes faced by the energy-stress tensor (in the presence of pressure) which is used to model the matter content of the universe, including dark energy.      

Error analysis of a satellite interferometer navigation system

An orthogonal system of interferometry baselines aboard a geostationary satellite is considered primarily as a global positioning and navigation system. The mathematical model based on the relationship between the measured phase differences, the known transmitter positions, and other systematic error model parameters is derived. A generalized Least‐Squares estimation procedure is used for the solution of the unknown transmitter positions. Study of the effects of the various system and error model parameters on the position accuracy reveals that this accuracy is critically dependent on the baseline length and the magnitude of the random component of the measuring errors. With a 50‐m baseline, the obtainable accuracy at a frequency of 1.5 GHz is comparable to that of the NAVSTAR/ GPS system. Considering the interest and needs of the potential users for a multicapability system, this interferometry system is considered a major improvement over existing and planned navigation systems.     

Factors affecting technical efficiency of small-scale apple farms in Balochistan Plateau,Pakistan

In Balochistan, Agriculture is dominated by small-scale farmers and the apple production sector is confronted with the chronic constraint of low output per unit of input. Although some agricultural policies have been implemented in this province, studies on effectiveness and impacts of such policies over apple production and farmers’ performance are still limited. This study is an effort to bridge the research gap on this potential crop in the plateau by investigating technical and scale efficiency of 181 officially designated small-scale apple farmers in mountainous district Mastung in Balochistan; then explored factors that underlie differences in production inefficiency. A two-stage input-oriented Data Envelopment Analysis (DEA) methodology was employed to evaluate technical and scale efficiency followed by truncated bootstrapped regression framework to analyze the correlative determinants to efficiency. Average technical and scale efficiencies of larger landholders were higher than medium and small landholders. Analysis indicated that there is still ample scope for inefficient sample farmers to reduce the input use by 33% without compromising the given yield level. Maximum contributions to the total input savings were from the use of urea, farm yard manure (FYM) and labor-use. Farmer’s experience, farm ownership, irrigation constraints, and farmer’s access to trainings, credit and extension services significantly affected apple farmers’ technical efficiency. Based on the findings of this study, strategies are suggested to enhancing efficiencies by farmers’ capacity development through effective extension services and trainings and provision of adequate credit.